(1) Field of the Invention
This invention relates to a method of manufacturing a semiconductor device using the polyimide resin as the insulating layer.
(2) Description of the Prior Art
A thermosetting polyimide resin is used as a materials for forming an insulating layer in a semiconductor device having the multilayer wiring structure. Application of such polyimide resin into a semiconductor device is disclosed in the U.S. Pat. No. 3,700,497. In case of application of polyimide resin into a semiconductor device, it is the heat resistivity that is excellent as compared with that of other organic thermosetting resins. In addition, the polyimide resin can be etched with excellent reproduceability, particularly by the etching solution of hydrazine system and allows formation of fine patterns. This is a very important advantage for application into a semiconductor device. The etching technique using the eteching solution of hydrazine system is disclosed in the U.S. Pat. No. 4,218,283. In addition to the ordinary polyimide resin obtained by the condensation reaction of the polyamic acid, the polyimideiso-indroquinazo-linedione (PIQ) as described in this reference is also referred in this specification as the polyimide resin.
In case the polyimide resion is used as the interlayer insulator of the multilayer wiring structure, it is often required to repeat formation of the polyimide resin layers and patterning by the selective etchings. In such a case, the polyimide layer pattern formed precedingly is desirable to be insoluble for the etching solution in the succeeding etching process for forming the polyimide layer pattern. The etching rate of polyimide can be changed by adjusting the composition of etching solution, but an effective means for changing the etching rate of polyimide resin layer already formed for the particular etching solution have not been known. Particularly, if there is a means for lowering the etching rate of a part of the polyimide resin layer, it is useful for manufacturing of a semiconductor device.